[webkit-dev] JavaScriptCore: Garbage Collector Issue

[Max Hentschel]

Hello,

I watched the WWDC 2013 session on integrating JavaScript into native apps and 
so I implemented a JavaScript library for a Swift iOS app connecting via 
JavaScriptCore. Although I don’t really know if this mail list is the correct 
place to ask, I thought I’d give it a shot.
I really liked how easy it was to get Swift to work with JavaScript and vice 
versa. But I stumbled upon a problem when I was testing the performance of my 
app. I wrote a XCTest in Xcode which performs multiple calls of the JavaScript 
library (with loops) but it always stops or freezes after the 292nd call.
I guess that the JavaScriptCore context (or virtual machine) are not 
deinitialized after the method call was successful. I even tried a manual 
deinitialize but it still freezes. I looked up the allocations in Instruments 
and it shows multiple VM: JS garbage collector allocations which are still 
active in the app.
I wrote a question on StackOverflow with some code examples and the Instruments 
log:
http://stackoverflow.com/questions/30443993/javascriptcore-on-ios-vm-garbage-collector-not-automatically-emtpying
 
http://stackoverflow.com/questions/30443993/javascriptcore-on-ios-vm-garbage-collector-not-automatically-emtpying
but I haven’t received a single answer yet. I guess JavaScriptCore on iOS is 
still something that is not being used very much.

I would be very happy if someone could take a look into my problem and share 
thoughts on it. This is part of my bachelor thesis so it would really help me a 
lot.

Thank you in advance and best regards,
Max Hentschel


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[webkit-dev] Implementing Media Session API

[Matt]

Hi WebKit Developers!

I plan on implementing the Media Session API in WebKit. The Media Session API 
provides web developers the ability to respond to media keys on hardware such 
as keyboards and remote controls. The tentative spec can be found here: 
https://mediasession.spec.whatwg.org https://mediasession.spec.whatwg.org/ 
and my work on this will be behind a feature flag.

The main Bugzilla issue tracking the implementation can be found here: 
https://bugs.webkit.org/show_bug.cgi?id=145411 
https://bugs.webkit.org/show_bug.cgi?id=145411

Thanks,

Matt

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Re: [webkit-dev] JavaScriptCore: Garbage Collector Issue

[Geoffrey Garen]

Hi Max.

The best way to get help with a potential bug in JavaScriptCore is to post 
example code that reproduces the bug to bugs.webkit.org.

 I wrote a XCTest in Xcode which performs multiple calls of the JavaScript 
 library (with loops) but it always stops or freezes after the 292nd call.

Can you post a backtrace of all threads in the frozen state? You can get a 
backtrace from the debugger, or the sample command line tool, or the 
Instruments Time Profiler.

 I guess that the JavaScriptCore context (or virtual machine) are not 
 deinitialized after the method call was successful.

I don’t know what you mean by this. I don’t think this is a thing.

 I even tried a manual deinitialize but it still freezes.

Ditto.

Regards,
Geoff
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